Buggy code:
public class UIUtils { private static final Icon ICON_CANCEL = new ImageIcon ( UIUtils . class . getResource ( "icons//cancel.gif" ) ) ; private static final Icon ICON_OK = new ImageIcon ( UIUtils . class . getResource ( "icons//ok.gif" ) ) ; private static final Icon ICON_UP = new ImageIcon ( UIUtils . class . getResource ( "icons//up.gif" ) ) ; private static final Icon ICON_DOWN = new ImageIcon ( UIUtils . class . getResource ( "icons//down.gif" ) ) ; private static final Icon ICON_COLLAPSE_ALL = new ImageIcon ( UIUtils . class . getResource ( "icons//collapseall.gif" ) ) ; private static final Icon ICON_EXPAND_ALL = new ImageIcon ( UIUtils . class . getResource ( "icons//expandall.gif" ) ) ; private static final Icon ICON_REFRESH = new ImageIcon ( UIUtils . class . getResource ( "icons//refresh.gif" ) ) ; private static final ImageIcon ICON_CLEAR = new ImageIcon ( UIUtils . class . getResource ( "icons//clear.gif" ) ) ; private static final ImageIcon ICON_SHOW_MESSAGE = new ImageIcon ( UIUtils . class . getResource ( "icons//editor.gif" ) ) ; private static final ImageIcon ICON_EXPORT = new ImageIcon ( UIUtils . class . getResource ( "icons//export.gif" ) ) ; private static final ImageIcon ICON_NEW = new ImageIcon ( UIUtils . class . getResource ( "icons//new.gif" ) ) ; private static final ImageIcon ICON_EDIT = new ImageIcon ( UIUtils . class . getResource ( "icons//edit.gif" ) ) ; private static final ImageIcon ICON_BROWSE = new ImageIcon ( UIUtils . class . getResource ( "icons//browse.gif" ) ) ; private static final ImageIcon ICON_SAVE = new ImageIcon ( UIUtils . class . getResource ( "icons//save.gif" ) ) ; private static final ImageIcon ICON_TEST = new ImageIcon ( UIUtils . class . getResource ( "icons//test.gif" ) ) ; private static final ImageIcon ICON_ADD = new ImageIcon ( UIUtils . class . getResource ( "icons//add.gif" ) ) ; private static final ImageIcon ICON_REMOVE = new ImageIcon ( UIUtils . class . getResource ( "icons//remove.gif" ) ) ; public static JButton createHeaderButton ( ) { } public static JButton createChecklistButton ( ) { } public static JButton createTextboxButton ( ) { } public static JButton createRemoveButton ( ) { } public static JButton createCancelButton ( ) { } public static JButton createOKButton ( ) { } public static JButton createDownButton ( ) { } public static JButton createUpButton ( ) { } public static JButton createNewButton ( ) { } public static JButton createSaveButton ( ) { } public static JButton createEditButton ( ) { } public static JButton createSaveAsButton ( ) { } public static JButton createInsertButton ( ) { } public static JButton createDoneButton ( ) { } public static JButton createCreditsButton ( ) { } public static JButton createScreenCaptureButton ( ) { } public static JButton createTestButton ( ) { } public static JButton createSelectButton ( ) { } public static JButton createExpandAllButton ( ) { } public static JButton createCollapseAllButton ( ) { } public static JButton createRefreshButton ( ) { } public static JButton createActionButton ( Action action ) { } public static JButton createGotoButton ( ) { } public static JButton createLoadDefaultsButton ( ) { } public static JButton createCloseButton ( ) { } public static JButton createClearButton ( ) { } public static JButton createShowMessageButton ( ) { } public static JButton createFindButton ( ) { } public static JButton createReplaceFindButton ( ) { } public static JButton createReplaceButton ( ) { } public static JButton createReplaceAllButton ( ) { } public static JButton createExportButton ( ) { } public static JButton createBrowseButton ( ) { } public static JButton createAddButton ( ) { } public static JButton createAddClassButton ( ) { <START_BUG> return new JButton ( "Add<seq2seq4repair_space>Class..." ) ; <END_BUG> } public static JButton createAddArchivesButton ( ) { } public static JButton createAddFoldersButton ( ) { } public static JButton createInsertAssertionButton ( ) { } public static JButton createInsertWaitButton ( ) { } public static JButton createEmptyButton ( ) { } }

Fix:
return UIUtils . createAddButton ( ) ;